1. Field of the Invention
The present invention relates to a surface acoustic wave linear motor, a surface acoustic wave linear motor package, and a lens actuator adopting the surface acoustic wave linear motor package, and, more particularly, to a surface acoustic wave linear motor that can be driven in opposite directions along a predetermined path, a package including the surface acoustic wave linear motor, and a lens actuator that is capable of performing an optical zoom function by adopting the surface acoustic wave linear motor package.
The surface acoustic wave linear motor package according to the present invention is a housing for the motor that drives the movable part due to the deformation of the substrate or the wave motion at the surface of the substrate. The surface acoustic wave linear motor package has an additional function to improve the efficiency of the motor. The present invention enables the miniaturization and weight reduction of an actuating device, and therefore, the present invention can be suitably used in various kinds of applications, which require subminiature linear motor, such as portable communication terminals.
2. Description of the Related Art
With recent development of communication technologies and digital information processing technologies, portable communication terminal technologies integrated with various functions such as information process, operation, communication, and visual information input and output, have come to the front. Examples of such portable communication terminal technologies include personal digital assistants (PDAs) with digital camera and communication functions, and mobile phones with digital camera and PDA functions. As digital camera technologies progress and information storage capacities are increased, high-end digital camera modules are being increasingly mounted in the PDAs and the mobile phones.
As mega pixel image sensors are used in the digital camera modules, which are mounted, for example, in the portable communication terminals, the importance of additional functions, such as automatic focus and optical zoom, is being further highlighted. In order to realize the automatic focus and optical zoom functions in such small-sized digital camera modules, there is needed an actuator that satisfies various performance requirements, such as rapid start speed, low power consumption, and large displacement, while occupying relatively small volume. Especially, there is needed an actuator that is capable of corresponding to the increase of required displacement according to the improvement of the optical zoom function. However, a conventional magnetic actuator, such as a voice coil motor (VCM), has problems in that the increase of the displacement is limited, and power is continuously consumed while the zoom function is used. On the other hand, in the case that a lead screw is rotated by a rotary motor, such as a stepping motor, to linearly move a movable part, the mechanism is very complicated, and friction and noise are generated from a gear part. Also, the actuators using the voice coil motor and the stepping motor have a complicated structure. Consequently, it is difficult to manufacture the actuators inexpensively, and the miniaturization of the actuators is restricted.